This invention relates to a telephone communications system enabling call redirection for subsequent call events.
With telephone communications systems, services may require call redirection to an alternate call destination dependent upon events that occur during the duration of the call. With the current state of the art, the initiation of the call redirection is caused by a call event that has already occurred. The prior art supports call redirection in one of three ways. The most common approach is to xe2x80x9ccamp onxe2x80x9d the call by xe2x80x9chairpinningxe2x80x9d the call through an adjunct processor using telephone facilities. This enables the adjunct processor to monitor the call throughout the duration of the call. However, hairpinning can add substantial cost to the service because additional transmission facilities are required. If a specified call event is detected by the adjunct processor, the adjunct processor instructs the telephone switching center to establish another call to a specified call destination.
With the second approach, hairpinning is not utilized. Rather, a call between a telephone unit and an adjunct processor is established. From the dialog that occurs during the call, the adjunct processor determines that the call should be redirected to another telephone designation. A connection is established from the telephone unit and the telephone designation. At this time, the adjunct processor is not involved with the call and thus is not active in subsequent call processing.
With the third approach, a call between a telephone unit and an adjunct processor is established, enabling dialog between the adjunct processor and the telephone unit to occur. The call is consequently redirected to another telephone designation. Moreover, the adjunct processor sends an enabling trigger to the telephone switching center over a control link. If the specified call event occurs, the telephone switching center sends a query message over the control link to the adjunct processor, asking for the appropriate action to be taken. The adjunct processor responds with a redirection message that contains a specified call destination.
FIG. 1 corresponds to the hairpinning approach (the above-described first approach) and illustrates an architecture as embodied in prior art for attaching adjunct processor 103 to mobile switching center (MSC) 102 in order to provide wireless services. In this architecture, mobile subscriber unit 100 is provided services by MSC 102 through base station 101. Mobile subscriber unit 100 communicates with base station 101 over radio channel 106 requesting a call. Both control messages as well as voice transmission are supported by radio channel 106. Voice transmission is supported over facility 107 to a switching fabric contained in MSC 102. Adjunct processor 103 monitors and relays voice transmission to public switching telephone network (PSTN) 104 over facility 108 to facility 109. PSTN 104 establishes a voice connection to designated party 105 according to dialed digits entered by either mobile subscriber unit 100 or designated party 105 thus completing the call.
Adjunct processor 103 can reside at one of a number of network entities that are associated with a wireless intelligent network, including an intelligent peripheral (IP), a service node (SN), or a service control point (SCP). The IP performs specialized resource functions such as playing announcements, collecting digits, performing speech-to-text or text-to-speech conversions, recording and storing voice messages, and so forth. The SCP is a real-time database and transaction processing system that provides service control and service data functionality. The SN combines the capabilities of an IP and an SCP.
If adjunct processor 103 detects that a particular call event occurs during the call between mobile subscriber unit 100 and party 105, such as a disconnect indication from party 105, adjunct processor 103 issues control redirection message 110 to PSTN 104 to reconfigure a voice path between mobile subscriber unit 100 and party 111. Redirection message 110 is typically transported on a separate control link. PSTN 104 subsequently establishes a voice path through PSTN 104 to party 111.
FIG. 2 corresponds to the above described second approach and illustrates a wireless communications architecture utilizing a redirection directive in accordance with prior art. Mobile subscriber unit 120 communicates with base station 121 over radio channel 126 requesting a call. Voice transmission is supported over facilities 127 and 128 to adjunct processor 123 through MSC 122. Consequently, a full-duplex connection is established between a user of mobile subscriber unit 120 and adjunct processor 123, from which it is determined that the call should be redirected to telephone unit 125. Adjunct processor 123 sends redirection message 130 to MSC 122, instructing MSC 122 to establish voice connection 129 through PSTN 124 to party 125 and to remove voice connection 128. Thus, a voice path is completed between mobile subscriber unit 120 and party 125. At this time, adjunct processor 123 is no longer active with the call.
FIG. 3 corresponds to the above described third approach and illustrates an architecture using a two-stage approach as embodied in prior art for attaching adjunct processor 152 to landline switching center 151 in order to provide landline telephone services. With landline advanced intelligent networks, landline switching center 151 is typically identified as a service switching point SSP. In this architecture, telephone unit 150 is provided service by telephone switching center 151. However, as appreciated by one skilled in the art, this architecture is applicable to wireless services by incorporating a plurality of base stations, replacing landline switching center 151 with a mobile switching center, and utilizing mobile subscriber units as telephone units. Moreover, the term xe2x80x9ctelephone unitxe2x80x9d is applicable to a variety of telephone instruments including wired telephone sets, cordless telephones, mobile subscriber units, fixed wireless telephone sets and so forth.
In FIG. 3, telephone unit 150 communicates with landline switching center 151, requesting a call. This request is physically conveyed by a signal, which can be a digital message, on facility 156. Moreover, facility 156 also transports voice transmission once the call is established. Landline switching center 151 completes the call to party 154 over facility 157 through PSTN 153. Adjunct processor 152 is notified of the call by landline switching.center 151 by sending message 158 to adjunct processor 152. Messages 158, 159, 160, and 161 are transported on a control link between landline switching center 151 and adjunct processor 152.
Adjunct processor 152 arms landline switching center 151 in order to prepare landline switching center 151 for the possibility of a subsequent call event identified in arm event message 159. For advanced intelligent networks, arm event message 159 is specified as the Request_Report_BCM_Event message in Bellcore GR-1298-CORE and GR-1299-CORE, Issue 4, Revision 1, October 1998, pages 4-1 to 4-15 (SSP Processing of Triggers and Requested Events). Landline switching center 151 continues to process and monitor the call until the call event as specified in arm event message 159 occurs. If the call event occurs, landline switching center 151 stops processing, sends event query message 160 to adjunct processor 152, and waits for response message 161 from adjunct processor 152. GR-1298 and GR-1299 specify the event query message as the EDP-Request message for advanced intelligent networks. Adjunct processor 152 returns response message 161, which instructs landline switching center 151 about subsequent action, such as redirecting the call to a different party.
The present invention obviates the need for the adjunct processor to monitor the call or the need for a two-stage approach (the above described third approach) for redirecting the call while affecting a call contingent upon subsequent call events.
The apparatus and method of the present invention enables a telephone communications system to redirect a call by an adjunct processor, utilizing a control message having various directives for current and subsequent execution by a telephone switching center. The telephone communications system can function as a mobile switching center in a wireless communications system or a landline switching center in a landline telephone system. The adjunct processor may be implemented within a service control point, a service node, or an intelligent peripheral.
The adjunct processor includes program instructions to generate a control message in response to a request for telephone service, such as in response to a dialog between a user of a telephone unit and the adjunct processor. The telephone switching center includes program instructions to receive the control message, to redirect the call, and to redirect the call again in response to call events that may occur during the call when first redirected.
The control message contains a initial redirection telephone number associated with the first redirection and with designated telephone numbers associated with subsequent call events that can occur during the call after the call is redirected to the initial redirection telephone number. Alternatively, the control message may contain only designated telephone numbers associated with subsequent call events that can occur during the call in which the telephone unit is currently active.
Numerous other advantages and features of the present invention will become readily apparent from the detailed description of the invention and the embodiments thereof, from the claims, and from the accompanying drawings.